BMW Z4 review – engine, gearbox and technical highlights
The Z4 is a talented roadster with much in its favour, just don’t expect Boxster levels of tactility
The engines used in the Z4 come from BMW’s modular range of units, the 20i and 30i models using a 2-litre single-turbo four-cylinder developing 194bhp and 254bhp respectively. The Z4 received its mid-life facelift in the latter part of 2022 and at this point the 30i was quietly dropped having proved to be the slowest selling model in the range.
The range-topping M Performance M40i utilises the B58 3-litre ’six, again with a single (twin-scroll) turbocharger. The lone six-cylinder in the range offers quite a step up from the 20i, developing 335bhp and 369lb ft of torque.
At launch both models were only available with the familiar ZF eight-speed auto that’s almost ubiquitous across the BMW range. In some other markets the 20i could be ordered with a six-speed manual. There’s nothing wrong with the eight-speed auto – it shifts imperceptibly when cruising and is fast enough – if not quite as fast as the best dual-clutch systems – when driving harder, it just feels like it’s much more in keeping with an executive cruiser rather than a sporting roadster. That's where the late addition of the M40i Handschalter option comes in.
Translated as ‘hand shift’, this finally brought a six-speed manual to the Z4, but only with the largest engine and initially only in frozen deep green paint with a cognac interior. A further seven exterior paint finishes and four interior colours were added in early 2025. There were further tweaks to the Handschalter pack including mixed alloy wheels (19-inches at the front and 20 at the rear), bespoke auxiliary springs front and rear and remapping for the electronically adjustable rear dampers and a software change for the steering, traction control and differential.
The M40i’s straight-six is still a lovely engine to spend time with. A rich seam of torque is available from low down, giving the M40i a strong turn of pace (and helping to combat its circa. 1600kg kerb weight) and while it’s not the loudest of engines, it makes a muted but pleasant, mellow bellow. Opt for the Sport+ setting and it does get a little more vocal.
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While the 2-litre four-cylinders in the 20i and 30i might not be the most tuneful four-pots ever made, they still sound relatively inspiring, certainly more so than in the 3-series where they’re rather muted. They’ll pop and bang on the overrun and on full-bore upshifts when in Sport mode, and while the sound is augmented through the speakers it does have a more natural tone to it than in other BMWs. They’re keen to rev and deliver when it comes to precisely measured throttle inputs.
Like its six-cylinder relation the 20i’s soundtrack is artificially enhanced via the car’s audio system, but for much of the time it actually sounds better than the six-cylinder; fire it up and there’s a purposeful burble from the exhaust, with a greater vocal range around the rev counter. It feels like the most has been made of what genuine sound it has to offer, while the M40i has been sadly strangulated.
The 3-litre in the M40i has a further layer of sophistication than the four-cylinder units and has all the trademark six-cylinder smoothness you’d expect. In Comfort mode though it can end up being almost inaudible as the gearbox is keen to change up at every opportunity, keeping the revs down and the soundtrack muted. To get the best from it, Sport mode needs to be selected, and then it becomes more inspiring with a sharper, significantly more sporting feel about it. With a wide torque band it feels fast almost no matter which gear you’re in.
